Block Control+Alt+Delete

Question

I am doing an Online Quiz project in C#. The test client is a Windows Desktop Application running on Windows XP. I need to block the control+alt+delete key combination to prevent students from minimizing/closing the application.

Using PInvoke is okay for me.

I know this is definitely possible because I have seen three applications doing this. They are all proprietary, so I have no way of knowing how it was done.

Answer 1

I achieved a similar goal, but with a different tactic in a Time Tracker tool I whipped up. This will give you a form which takes over the screen - doesn't allow windows to appear on top of it and will shoot down task manager if it is started.

1. Set your form TopMost = True.

2. override the Form.OnLoad method like so:

   protected override void OnLoad(EventArgs e)
   {
       base.OnLoad(e);
       this.Location = SystemInformation.VirtualScreen.Location;
       this.Size = SystemInformation.VirtualScreen.Size;
   }
   

3. Create a timer, with a 500 millisecond interval, which looks for, and kills "taskmgr.exe" and "procexp.exe".

4. Override the Form.OnFormClosing:

   protected override void OnFormClosing(FormClosingEventArgs e)
   {
       if (e.CloseReason == CloseReason.UserClosing || e.CloseReason == CloseReason.FormOwnerClosing)
       {
           MessageBox.Show("Nice try, but I don't think so...");
           e.Cancel = true;
           return;
       }
       base.OnFormClosing(e);
   }
   

5. Override OnSizeChanged:

   protected override void OnSizeChanged(EventArgs e) {
       base.OnSizeChanged(e);
       this.WindowState = FormWindowState.Normal;
       this.Location = SystemInformation.VirtualScreen.Location;
       this.Size = SystemInformation.VirtualScreen.Size;
       this.BringToFront();
   }